Condensed Matter Zoom Seminar | Eugene Demler, Harvard | "A new perspective on magnetic polarons from cold atoms"

Wed, Mar 31, 2021, 2:00 pm

What can we learn about a many-body system when we measure every constituent particle? Current experiments with ultracold atoms provide snapshots of many-body states with single particle resolution. I will present a recent application of this method to study magnetic polarons in antiferromagnetic Mott insulators. In the low doping regime, signatures of polaronic dressing of individual dopants can be found in higher order spin-charge correlation functions both in equilibrium and in dynamics. Experiments indicate that magnetic polarons are accurately described as spinon-chargon pairs bound by geometric strings, in close analogy to quark-antiquark bound pairs forming mesons in QCD. Numerical analysis of the t-J model provides further evidence for the bound states indicating the existence of rotational excitations that can be probed with ARPES type experiments. At higher doping the system undergoes crossover into the Fermi liquid state, as revealed by conventional observables, such as spin susceptibility, and higher order correlation functions.